Table 1.

Relevant factors influencing (a) snow depth, (b) NDVI for the 1st of May, body mass of adult (c) female and (d) male red deer, (e) date of migration start.

parameter	biological interpretation
(a) snow depth
altitude	more snow with increasing altitude
NAO in winter×altitude	less snow depth with higher NAO-values during winter at low altitude, while more snow at high altitude
(b) NDVI-greenness
NAO in winter×proportion of low-altitude habitats	greenness is delayed with high NAO-values during winter at high altitude, but less so at low altitude
NAO in April×proportion of low-altitude habitats	greenness is delayed with high NAO-values during April at high altitude, but less so at low altitude
(c) body mass adult female red deer
NAO in winter	high NAO-values during winter corresponds to higher body mass
NDVI (yearly)	early vegetation start in a year corresponds to higher body mass
NDVI (spatial)	early vegetation start in one place comparing to others corresponds to higher body mass
(d) body mass adult male red deer
NAO in winter	high NAO-values during winter corresponds to higher body mass
NDVI (yearly)	early vegetation start in a year corresponds to higher body mass
NDVI (spatial)	early vegetation start in one place comparing to others corresponds to higher body mass
(e) migration date
NDVI	migration begins earlier when vegetation green-ness starts earlier in the winter range

All factors reported below were significant, and the detailed results are presented in the electronic supplementary material, tables 2 and 3.